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La Carrera Panamericana

3K views 10 replies 5 participants last post by  Dimitri 
#1 ·
This is an Amazon I built last year for La Carrera, which is a gonzo 2000 mile endurance race from the southern end of Mexico to the Texas border. The 2009 running starts with qualifying on Friday the 23rd of this month, and the race starts the Saturday after that and goes for a week. Wish us luck (I feel I'm part of the team, even though I'm not going)...

http://www.applefarmerracing.com/
 
#3 ·
Re: La Carrera Panamericana (gdill2)

Super cool!

Iceracing friend of mine (Kip Moncreif) did it last year in a Bio-diesel Mercedes.

Would love to run it myself, partial motivation for the current restoration of '63 p1800. Probably just a hillclimber for now but Mexico is calling.

I Did the 24 hours of LeMons last week at Nelson Ledges in a '71 SAAB 99, thinking about a beater p1800 or Amazon for next year.

Josh Teresco
 
#5 ·
Re: La Carrera Panamericana (exizldelfuego)

The race went rather well, despite a technical glitch that had the car running on three cylinders most of the first day. Long story short: 1st in class, 16th overall in a field that started with 102 cars. Steve Berry has a ton of photos, commentary, and some pretty cool in-car videos here:

http://www.applefarmerracing.com/2009.html

Kudos to Richard for driving the &%$# out of the car, Nate for a flawless job navigating, Oddvar, Willy and Steve for ace wrench work, and Al for getting everyone where they needed to be when they needed to be there.

 
#6 ·
Re: La Carrera Panamericana (Phil Singher)

Incredible story. 125 mph for an Amazon seems a bit ... high. I suspect you had the B20 with the big valves. How much hp do you think that engine have? What type of carbs did you have. I like your cold air box, but what did you do to that battery? What type of transmission and what rear end ratio did you have? Looks like you had very low profile tires. Were you using the ipd set up for springs and anti-rol bars?

d
 
#7 ·
Re: La Carrera Panamericana (Dimitri)

Quote, originally posted by Dimitri »
Incredible story. 125 mph for an Amazon seems a bit ... high. I suspect you had the B20 with the big valves. How much hp do you think that engine have? What type of carbs did you have. I like your cold air box, but what did you do to that battery? What type of transmission and what rear end ratio did you have? Looks like you had very low profile tires. Were you using the ipd set up for springs and anti-rol bars?

http://www.applefarmerracing.com/car.html

George Dill
 
#8 ·
Re: La Carrera Panamericana (Dimitri)

Engine is set up for a very wide torque band rather than peak power, and to be a durable as possible. It only dynoed at 163 HP brand new, not the most powerful engine I've built by any means. Power probably came up a bit as it broke in more.

Carbs are Weber 48DCO. Battery had already been moved to the trunk for better weight distribution when the car came to my shop.

Overdrive transmission, 4.30 gears w/ limited slip.

Tires are 205VR60-15. Rules limited us to 6" wide wheels, and we didn't want lower profile tires, there being a good chance of hitting big potholes at 100 MPH.

Springs are the VPD progressive fronts and somewhat stiffer rears. IPD sway bar in front only.
 
#9 ·
Re: La Carrera Panamericana (Phil Singher)

Hey, thanks all, nice writeup. A couple of comments/questions:

The huge stock crank and rod bearings heat up the oil due to shearing a large quantity of oil. Its not really friction (no metal-to-metal), its viscous shear (but close I guess). Could't you deal with the excessive oil temperatures with an aggressive oil cooler and a good synthetic oil of not too hgh viscosiity (i.e., 10w30)? The huge bearings will also give you an extra protection in case something goes wrong (in case, of say, overheating). The new pistons with less skirt area will probably reduce the viscous friction loss at high speeds, but stock type pistons would probably give you longer life of the piston rings (less piston rocking, a bit larger clearance so easier to deal with tolerance), yes?

At what rpm would the peak power and peak torque come?

Thanx
 
#10 ·
Re: La Carrera Panamericana (Dimitri)

The crank stuff was probably overkill and I did use a large oil cooler, but we did everything we could to err on the side of safety. Four or five days of the race are run at high altitude (Mexico City is above 7000' and Zacatecas over 8000') where cooling is less effective, and the speed stages on the last day involve holding the car near top speed for 20 miles at a time.

I don't like to use synthetic oil until an engine has broken in thoroughly, and there was no chance to do that. We ran Brad Penn racing oil, which is just exactly the old Kendall green oil under a different brand name. The pan has a windage tray.

The pistons and rings needed to go 2500 miles. In fact, they went more like 5000, as the engine also completed the 2008 running. It is starting to show some leak down now, I'm told. Top rings are very thin and gas-relieved to minimize friction, so that's not surprising. I would not use such pistons in a street engine, for sure (although I do use Ross pistons in them).

Peak HP is right at 6000, peak torque at 4800, but it's within 10% of peak torque from 3000 to 6000. We ran it to 7500 on the dyno a bunch of times. Driver and navigator never know what the next turn is really going to be like and what gear is optimum, so it had to be very tractable and forgiving, while being just barely fast enough to win.
 
#11 ·
Re: La Carrera Panamericana (Phil Singher)

Thanks for the info.

What I should have said for the crank bearings, is that you can reduce internal heating of the oil by increasing clearance.

Journal bearings tend to be forgiving and self adjusting. If the viscous shear heats the oil, the oil thins (reduced viscosity). That causes two things: One, the flow through the bearing increases, and two, the shear heating decreases. If the temperature gets too high though, the oil can oxidize and lose its properties. That's where the synthetic helps. And if the oil cooler is oil/water like in the stock P1800, the reduced air density should not be such a big issue (assuming that the main radiator can cool down the engine, which it might, since along with cooling capacity you also lose power due to reduced air density). If synthetic is out of the question due to cam not fully broken in (I suspect these piston rings break in rapidly), a straight weight (i.e., a 30W rather than 10w30) may be better.

All this is of course theoretical, and you fellows may have practical info on what works for this particular type of engine.

Thanks again.
 
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